Housing for photoelectric sensing unit



IN VEN TORS RA LPl-l E. KLAUSS RICHARD J. SWARTHOUT Filed Aug. 9, 1961R. J. SWARTHOUT ET AL HOUSING FOR PHOTOELECTRIC SENSING UNIT July 30,1963 United States Patent 3,099,750 HOUSING FOR PHOTOELECTRIC SENSINGUNIT Richard J. Swarthout and Ralph E. Klauss, Rochester, N.Y.,assignors to Eastman Kodak Company, Rochester, N.Y., a corporation ofNew Jersey Filed Aug. 9, 1961, Ser. No. 130,402 4 Claims. (Cl. 250-239)This invention relates to a photoelectric sensing unit especiallyintended for sensing marks on a web either by reflected or transmittedlight depending upon the character of the web and/ or the mark.

In the processing of photographic prints it is customary to handle theprints in the form of long strips and, after processing to out theindividual pictures from one another. To facilitate the cuttingoperation, it is usual to provide marks near the edge of the strip,which may be utilized to cause actuation of the cutting mechanism. Inorder to perform this entire operation automatically it is necessary toprovide a sensing unit for sensing the marks along the edge of the stripand to use the output of this unit to trigger the cutting mechanism atthe appropriate time. Photoelectric sensing units can, of course, beused for this purpose. However in the use of such photoelectric sensingunits problems arise due to the fact that various types and/or locationsof marks may be employed, some of which may be more readily sensed bytransmitted light while, for others, reflected light more eflicientlysenses the mark. Moreover, in either case stray light may so lower thesensitivity of the sensing unit, that it will fail to respond properlyto the marks and thereby cause improper cutting action.

It is therefore an object of this invention to provide a photoelectricsensing unit which is readily adapted for use in sensing marks on amoving web, either by transmitted or by reflected light.

A further object of this invention is to provide a unit which includesits own light source and is arranged to effectively eliminate any straylight so as to insure that the only light reaching the photoelectricunit comes from such source.

It is a further object to provide such an apparatus which is ofrelatively simple construction and yet which is very effective for theintended purpose.

Further objects will become apparent from the following description andclaims particularly when considered in the light of the accompanyingdrawings wherein:

FIG. 1 is a side view of the sensing unit with parts broken away betterto show the internal construction thereof;

FIG. 2 is a fragmentary view showing the lower portion of the unitprovided with a modified head of the type used for sensing marks bytransmitted, rather than reflected, light; and

FIG. 3 is a view of the sensing head used in the form shown in FIG. 2.

Considering first the form of the invention shown in FIG. 1, the sensingunit comprises a main housing 1, preferably of light-tight construction,spaced slightly above the plane of movement of the web or strip 2hearing the marks tobe sensed. Mounted within the portion 3 of housing 1at one end thereof, is a photocell 4, the cathode 5 of which isdiagrammatically represented. The portion 3 of housing 1 includes apassageway 6 extending axially downwardly toward the plane of the web. Atubular member 7 forming the upper portion of a head unit 7 is secured,as by a set screw 8, in a mating socket 9 formed in the lower wall ofthe housing 1 and extends downwardly toward the plane of the web 2 withits hollow interior axially aligned with the passageway 6, therebyafiording a passageway for light from the exterior of "ice the housingto the cathode 5 of photocell 4. Resiliently supported from the lowerend 10 of tubular member 7 is a presser foot or button 12, preferablyformed of a low friction material, such as Teflon, and which is arrangedto loosely, telescopically receive the lower portion 10 of the tubularmember 7. The lower Wall 13 of presser-foot 12 is provided with anopening 14 axially aligned with the passageway 6 and which effectivelydetermines the inspection area on the web 2. The button or presser-foot12 may conveniently be supported for limited resilient movement towardand away from the main housing 1 by means of a suitable leaf spring asindicated at 15.

Mounted within the housing 1 by means of a suitable bracket 16 is asmall lamp or light source 17, the interior walls forming portion 3 ofhousing .1 serving to effectively shield the photocell 4 from directrays from light source 17. Light from this source 17 is arranged to passthrough a suitable opening 18 in housing portion 3 and impinge upon asmall mirror 19 located the passageway 6 and arranged to reflect lightfrom the source 17 downwardly through the tubular member 7 and theopening 1 4 in the presser foot so as to illuminate the inspection areaof web 2. Light reflected from the surface of the web 2 is thenreflected upwardly through the tubular member 7 and passageway 6 tocathode 5 of photocell 4. As can be readily seen in FIG. 1 a suitablelens 20 is provided in the passageway 6 to direct the rays of light fromlamp 17 into an approximate focus at the plane of the Web 2 and toconcentrate the reflected rays at the cathode 5 of photocell 4. As canbe seen in FIG. 1 the mirror 19 is arranged so that it effectively masksone-half of the lens so that with this arrangement the single lens 20can serve to thus focus both the outgoing and the reflected rays oflight. The electrical leads for supplying current to the light source 17and the photocell 4 may be arranged as indicated at 21 and 22 and cabledtogether where they exit from the housing 1 as indicated at 23.

With the arrangement shown in FIG. 1 light from source 17 will bereflected by the optical system including mirror 19 and lens 20 onto themoving surface of the web 2. Light reflected from this surface will beredirected by lens 20 onto the cathode 5 of photocell 4. Whenever a markof a distinctive character passes by the opening 14 in presser-foot 12,the amount of light reaching the photocell 4 will be increased ordiminished, as the case may be, and a corresponding output signal willbe produced across the photocell, which may be amplified by conventionalmeans, not shown, and used to trigger print cutting machinery or for anyother purpose desired. The arrangement of the presser-foot 12 is suchthat it effectively defines the inspection area, by means of the opening14, and, at the same time, effectively prevents extraneous light fromgetting into the interior of tubular member 7 and/or passageway 6 andthereby affecting the sensitivity of the photocell. Spring 15 tends tourge the presser-foot into firm sliding contact with the web 2 therebyremoving any wrinkles which might be in the general area being inspectedand which might otherwise cause a misfunction of the unit. However, byvirtue of the resilience of the spring 15, variations in the thicknessof the film at splices or for other reasons may be readily accommodated.Since the presser-foot is preferably made of low-friction material, itwill not produce any undesirable scratching or marking of the Websurface nor produce an undue amount of friction drag on the web orstrip.

When it is desired to sense marks by means of transmitted, rather thanreflected light, an alternative head arrangement is utilized as shownFIGS. 2 and 3. To

this end, the head unit 7 formed by sleeve 7 and the associatedpresser-foot 12 is removed from the socket 9 of housing 1, and the headunit sleeve 27 is inserted in its stead. Head unit 27 includes a tubularportion 27' carrying at its lower end a generally C-shaped bracketmember 28, the lower leg 29 of which carries a socket 30 for a lamp orlight source 31. A guide member 32 is secured to bracket 28 in generallyparallel, closely spaced relationship to the bottom wall 3-3 of tubularportion 27'. Both the bottom wall 33 and guide member 32 are providedwith aligned openings 34 and 35 respectively which provide for passageof light from the light source 31 through the hollow interior of tubularportion 27' and via lens 20 and passageway 6 to the cathode of photocell4. As shown in FIGS. 2 and 3, the spacing between guide member 32 andbottom wall 33 is such as to fairly closely receive the web 2 to beinspected, the C-shaped bracket 28 providing clearance for the edge ofthe web so that the light source may be properly supported in thedesired location.

When sensing head 27 is to be that the internal light source light fromthis latter source will not interfere with that provided by source 31.In order to accomplish this result, a suitable closed circuit switchingjack is mounted in the end wall of housing 1. This jack is so connectedthat its normally closed switching points 41 complete the electricalcircuit to lamp 17 when operation with head 7 is involved as shown inFIG. 1. However, when it is desired to use the alternative head 27, aplug 42 carried on the end of the supply cable 43 for lamp 31 isinserted in jack 40 so as to bring the electrical connections from thesupply leads 2.2 to lamp 31 and, at the same time, to open the normallyclosed connections at 41 so as to extinguish lamp 17. This result isproduced merely by in sorting the plug 42 into the jack as indicated inFIG. 2.

Operation of the FIG. 2 embodiment is, of course, quite similar to thatof the previously described embodiment except that the light reachingthe photocell cathode 5 is light which has been transmitted through theweb 2 rather than reflected from the surface thereof. Guide member 32with its depending flanges 46 and 47 serves not only as a means to tionpast the inspection apparatus but also serves to pre vent extraneouslight from passing through the opening 34 and thence to the photocell 4.

As will be readily apparent to those skilled in the art, the specificunits shown are merely representative of the invention, and manyvariations and modifications can be made without departing from thespirit and scope of the invention as defined by the appended claims.

We claim:

1. A photoelectric unit for sensing the light reflecting properties of asurface to be inspected comprising a gen erally light-tight housing, alight source and a photocell mounted Within said housing with saidphotocell shielded from direct light from said source, means including atubular member providing a passageway for light through one wall of saidhousing, a presser foot and means resiliently mounting said presser footadjacent the outer end portion of said tubular member for limitedmovement axially thereof, said presser foot having a portion loose- 1ytelescopically receiving said outer end portion of said utilized, it isnecessary 17 be extinguished so that guide the web into properpositubular member and having an opening through its end wall insubstantially axial alignment with said passageway, said presser footmounting means resiliently biasing said presser foot in an axial outwarddirection relative to said tubular member and means for directing lightfrom said source outwardly through said passageway and opening onto asurface to be inspected and such of said light as is reflected by saidsurface back through said opening and said passageway and onto saidphotocell.

2. A photoelectric unit as in claim 1 wherein said light directing meansincludes a single lens common to both the outgoing and reflected lightpaths.

3. A photoelectric unit comprising a housing, a light source and aphotocell carried within said housing, said photocell being shieldedfrom direct light from said source, means including a generally tubularmember projecting outwardly beyond one wall of said housing andproviding a passageway for light through said wall, a presser foothaving a portion arranged to loosely telescopically receive the outerend of said tubular member and having an end wall provided with anopening therethrough, means resiliently mounting said presser foot forlimited telescopic movement relative to said tubular member and withsaid opening in axial alignment with said passageway, said presser footmounting means resiliently biasing said presser foot in an axial outwarddirection relative to said tubular member and means for directing lightfrom said source outwardly through said passageway and opening and todirect light from said source which is reflected back through saidopening and said passageway onto said photocell.

4. A photoelectric unit for sensing the optical properties of a web andcomprising a housing, a photocell mounted within said housing, a headmember carried by said housing and protruding outwardly beyond one wallof said housing, said housing and said head member being provided withaligned passageways forming a light path from the outer end of said headmember to said photocell, said head member comprising means including awall extending transversely of the passageway in and forming said outerend of said head member and adapted to be positioned substantiallyagainst aweb to be in spected and provided with an opening therethroughin axial alignment with said passageway for restricting the lightreaching said photocell to light passing through said opening from theweb, said head member further comprising resilient means mounting saidtransverse wall for limited movement relative to said housingsubstantially axially of the passageway in said head member, saidmounting means resiliently urging said transverse wall in an outwarddirection relative to said housing and means including a light sourcefor illuminating that portion of the web in the area of said opening.

References Cited in the file of this patent UNITED STATES PATENTS2,226,677 Vikhm-an Dec. 31, 1940 2,458,926 Bassett Jan. 11, 19492,688,099 Bickley Aug. 31, 1954 2,712,611 Nyman July 5, 1955 2,916,624Angel et a1 Dec. 8, 1959 2,920,209 Asten Jan, 5, 1 960

1. A PHOTOELCTRIC UNIT FOR SENSING THE LIGHT REFLECTING PROPERTIES OF ASURFACE TO BE INSPECTED COMPRISING A GENERALLY LIGHT-TIGHT HOUSING, ALIGHT SOURCE AND A PHOTOCELL MOUNTED WITHIN SAID HOUSING WITH SAIDPHOTOCELL SHIELDED FROM DIRECT LIGHT FROM SAID SOURCE, MEANS INCLUDING ATUBULAR MEMBER PROVIDING A PASSAGEWAY FOR LIGHT THROUGH ONE WALL OF SAIDHOUSING, A PRESSER FOOT AND MEANS RESILIENTLY MOUNTING SAID PRESSER FOOTADJACENT THE OUTER END PORTION OF SAID TUBULAR MEMBER FOR LIMITEDMOVEMENT AXIALLY THEREOF, SAID PRESSER FOOT HAVING A PORTION LOOSELYTELESCOPICALLY RECEIVING SAID OUTER END PORTION OF SAID TUBULAR MEMBERAND HAVING AN OPENING THROUGH ITS END WALL IN SUBSTANTIALLY AXIALALIGNMENT WITH SAID PASSAGEWAY, SAID PRESSER FOOT MOUNTING MEANSRESILIENTLY BIASING SAID PRESSER FOOT IN AN AXIAL OUTWARD DIRECTIONRELATIVE TO SAID TUBULAR MEMBER AND MEANS FOR DIRECTING LIGHT FROM SAIDSOURCE OUTWARDLY THROUGH SAID PASSAGEWAY AND OPENING ONTO A SURFACE TOBE INSPECTED AND SUCH OF SAID LIGHT AS IS REFLECTED BY SAID SURFACE BACKTHROUGH SAID OPENING AND SAID PASSAGEWAY AND ONTO SAID PHOTOCELL.